public static BMPImage ConvertDDSToBMP(DDSImage dds)
{
//Creates new empty BMP file
BMPImage bmp = new BMPImage((UInt32)dds.Width, (UInt32)dds.Height);
//container for colors
RGBColor[] colors = new RGBColor[4];
int texelsX = (int)dds.Width / 4;
int x, y = 0;
//iterates through all data in DDS file
for (int i = 0; i < dds.ImageDataLength; i++)
{
DDSImage.TexelBlock t = dds.GetImageData(i);
colors = ReadMainColors(t);
RGBColor color = new RGBColor(0,0,0);
byte[] texelCol = new byte[4];
for (int k=0;k<t.blocks.Length;k++)
{
texelCol[0] = (byte)(t.blocks[k] & 0x3);
texelCol[1] = (byte)((t.blocks[k] & 0xC) >> 2);
texelCol[2] = (byte)((t.blocks[k] & 0x30) >> 4);
texelCol[3] = (byte)((t.blocks[k] & 0xC0) >> 6);
for (int j = 0; j < 4; j++)
{
color = colors[texelCol[j]];
x = (i % texelsX) * 4 + j;
y = ((int)dds.Height - 1) - ((i / texelsX) * 4) - k;
bmp.AddImageData(x, y, color);
}
}
}
bmp.Save(dds.FileName);
return bmp;
}
public static DDSImage ConvertBMPToDDS(BMPImage bmp)
{
// In this algorithm (0,0) is the lower left corner because BMP data starts from there
DDSImage dds = new DDSImage(bmp.Width,bmp.Height);
for (int y = 0; y< bmp.Height; y += 4)
{
for (int x = 0; x < bmp.Width; x += 4)
{
RGBColor[] block = new RGBColor[DDSConst.DDS_BLOCK_SIZE];
for (int i = 0; i < block.Length; i++)
{
block[i] = bmp.GetImageData(x +(i%4) , (int)bmp.Height - 1 - (y + (i / 4)));
}
dds.AddImageData(CompressDataBlock(block));
}
}
dds.Save(bmp.FileName);
return dds;
}
/// <summary>
/// Converts RGB888 (3 bytes) to RGB565 (2 bytes)
/// </summary>
/// <param name="rgb">RGB888</param>
/// <returns>RGB565</returns>
public static UInt16 ConvertRGB888ToRGB565(RGBColor rgb)
{
UInt16 b = (UInt16)((byte)(rgb.B >> 3) & 0x001F);
UInt16 g = (UInt16)(((byte)(rgb.G >> 2) << 5) & 0x07E0);
UInt16 r = (UInt16)(((byte)(rgb.R >> 3) << 11) & 0xF800);
return (UInt16)(b | g | r);
}
public static float ColorBrightness(RGBColor rbg)
{
return 0.2126f * rbg.R + 0.7152f * rbg.G + 0.0722f * rbg.B;
}
/// <summary>
/// Returns smaller color, combined of min values from R, G, B channels
/// </summary>
/// <param name="value1"></param>
/// <param name="value2"></param>
/// <returns></returns>
public static RGBColor Min(RGBColor value1, RGBColor value2)
{
RGBColor result = new RGBColor(
Math.Min(value1.R, value2.R),
Math.Min(value1.G, value2.G),
Math.Min(value1.B, value2.B));
return result;
}
private static DDSImage.TexelBlock CompressDataBlock(RGBColor[] block)
{
//Finds max and min color
RGBColor maxColor = new RGBColor(0, 0, 0);
RGBColor minColor = new RGBColor(255, 255, 255);
float max = 0;
float min = 255f;
for (int i = 0; i < block.Length; i++)
{
//Note: Testing Luminance to determine max and min color, but having some artifacts on pic
/*
if(max<Math.Max(max, ImageUtils.ColorBrightness(block[i])))
{
max = Math.Max(max, ImageUtils.ColorBrightness(block[i]));
maxColor = block[i];
}
if (min > Math.Min(min, ImageUtils.ColorBrightness(block[i])))
{
min = Math.Min(min, ImageUtils.ColorBrightness(block[i]));
minColor = block[i];
}*/
maxColor = ImageUtils.Max(maxColor, block[i]);
minColor = ImageUtils.Min(minColor, block[i]);
}
DDSImage.TexelBlock tb = new DDSImage.TexelBlock();
tb.blocks = new byte[4];
UInt16 color2 = 0;
UInt16 color3 = 0;
tb.color0 = ImageUtils.ConvertRGB888ToRGB565(maxColor);
tb.color1 = ImageUtils.ConvertRGB888ToRGB565(minColor);
//Interpolate color2 and color3
int B = (int)(((2.0f / 3.0f) * maxColor.B) + ((1.0f / 3.0f) * minColor.B));
int G = (int)(((2.0f / 3.0f) * maxColor.G) + ((1.0f / 3.0f) * minColor.G));
int R = (int)(((2.0f / 3.0f) * maxColor.R) + ((1.0f / 3.0f) * minColor.R));
color2 = ImageUtils.ConvertRGB888ToRGB565(new RGBColor(R, G, B));
B = (int)(((1.0f / 3.0f) * maxColor.B) + ((2.0f / 3.0f) * minColor.B));
G = (int)(((1.0f / 3.0f) * maxColor.G) + ((2.0f / 3.0f) * minColor.G));
R = (int)(((1.0f / 3.0f) * maxColor.R) + ((2.0f / 3.0f) * minColor.R));
color3 = ImageUtils.ConvertRGB888ToRGB565(new RGBColor(R, G, B));
float[] distances = new float[4];
int colorTableColIndex = 0;
int colorTableRowIndex = 0;
int colorTableRow = 0;
//iterates through 16 block of colors
for (int x = 0; x < block.Length; x++)
{
UInt16 rgb565 = ImageUtils.ConvertRGB888ToRGB565(block[x]);
//Euclidean distance between the two colors, no need to sqrt for comparison
distances[0] = (float)Math.Pow(tb.color0 - rgb565, 2f);
distances[1] = (float)Math.Pow(tb.color1 - rgb565, 2f);
distances[2] = (float)Math.Pow(color2 - rgb565, 2f);
distances[3] = (float)Math.Pow(color3 - rgb565, 2f);
//Find minimum distance from calculated values
float minDistance = distances[0];
int indexBlock = 0;
for (int i = 1; i < 4; i++)
{
if (distances[i] < minDistance)
{
minDistance = distances[i];
indexBlock = i;
}
}
//Write the index value to correct position in this color table row
switch (colorTableColIndex)
{
case 0:
colorTableRow = indexBlock;
break;
case 1:
colorTableRow |= (indexBlock << 2);
break;
case 2:
colorTableRow |= (indexBlock << 4);
break;
case 3:
colorTableRow |= (indexBlock << 6);
break;
}
colorTableColIndex++;
//If all four values have been written to this color table row,
//Save it to texel block structure and start getting data from next row
if (colorTableColIndex == 4)
{
tb.blocks[colorTableRowIndex] = (byte)colorTableRow;
colorTableRowIndex++;
colorTableColIndex = 0;
}
}
return tb;
}
private static RGBColor[] ReadMainColors(DDSImage.TexelBlock texel)
{
RGBColor[] colors = new RGBColor[4];
RGBColor rgbColor0 = ImageUtils.ConvertRGB565ToRGB888(texel.color0);
RGBColor rgbColor1 = ImageUtils.ConvertRGB565ToRGB888(texel.color1);
RGBColor rgbColor2 = new RGBColor(
(int)((2.0f / 3.0f) * rgbColor0.R + (1.0f / 3.0f) * rgbColor1.R),
(int)((2.0f / 3.0f) * rgbColor0.G + (1.0f / 3.0f) * rgbColor1.G),
(int)((2.0f / 3.0f) * rgbColor0.B + (1.0f / 3.0f) * rgbColor1.B));
RGBColor rgbColor3 = new RGBColor(
(int)((1.0f / 3.0f) * rgbColor0.R + (2.0f / 3.0f) * rgbColor1.R),
(int)((1.0f / 3.0f) * rgbColor0.G + (2.0f / 3.0f) * rgbColor1.G),
(int)((1.0f / 3.0f) * rgbColor0.B + (2.0f / 3.0f) * rgbColor1.B));
colors[0] = rgbColor0;
colors[1] = rgbColor1;
colors[2] = rgbColor2;
colors[3] = rgbColor3;
return colors;
}
public void AddImageData(int x, int y, RGBColor rgb)
{
imageData[x, y] = rgb;
}
/// <summary>
/// Loads and reads BMP file
/// </summary>
/// <param name="fileName"></param>
public void Read(string fileName)
{
byte[] rawData = File.ReadAllBytes(fileName+ EXTENSION);
using (MemoryStream ms = new MemoryStream(rawData))
{
using (BinaryReader br = new BinaryReader(ms))
{
//read header
if (fileHeader.Parse(br))
{
//read DIBHeader
dibHeader.Parse(br);
//read data
imageData = new RGBColor[Width, Height];
for (int y = 0; y < Height; y++)
{
for (int x = 0; x < Width; x++)
{
//Colors channels are stored in b,g,r order
byte b = br.ReadByte();
byte g = br.ReadByte();
byte r = br.ReadByte();
imageData[x, y] = new RGBColor(r, g, b);
}
}
}
else { Console.WriteLine("Wrong data"); }
}
}
}
